Today there is an increasing demand for implementation of new and fast access technologies and transmission technologies. There is also a demand for a capability to mix different access technologies. ADSL (Asymmetric Digital Subscriber Line) is a high speed transmission technology using copper wires from a central office to subscriber premises. It has a high downlink capacity and a considerably lower uplink capacity. The technology has evolved among others resulting in VDSL (Very high data rate Digital Subscriber Line), but the transmission speed goes down considerably with the length of the copper wire and the sites or line boards have to be located close to the end user. In for example an Ethernet network topology comprising a number of switches or switching nodes and end-user line boards, for example implementing VDSL (e.g. VDSL(2)), it is very important that the subscriber terminations are known by the management system or the operator in order to be able to offer a correct subscriber configuration. If it is not possible to locate and to identify which are the IP addresses of the line boards that are associated with the subscriber terminations, it is not possible for a management system or an operator to handle IP management operations for example over SNMP (Simple Network Management Protocol) of the correct switching node to manage and configure subscriber connections for example over a VDSL line. Today existing solutions comprise an access node arrangement based on a fixed Ethernet setup, and are based on physical cabling and learning of MAC (Medium Access Control) addresses in order to detect the topology. Such an access node arrangement comprises a controlling node or an aggregation switch handling for example private IP addresses, inventory, alarms etc. and controlling of line boards either directly or over aggregation switches or, more generally switching nodes.
In known systems the equipment is provided at the central office, which can be located far away from the end-users, and a fixed line board port numbering per termination is used. This means that is not possible to provide for an extension e.g. with a new level. In known solutions MAC tables are provided in the switching nodes and reading of MAC tables is required for topology learning purposes. This is possible for small access nodes in for example a fixed Ethernet topology or similar since the number of switching levels is limited. If for example larger access node arrangements are needed which are based on distributed topologies, such as for example ring structures with many small sites (here a site means a switching node and line boards), it gets very complicated and slow to base topology learning on reading of MAC tables mapping a MAC address of a line board to an IP address of the line board. Thus, hitherto it has been necessary to read MAC tables in the switching nodes, or aggregation switches, for registering a hardware unit in the management system. In order to identify a subscriber to perform a management operation it is necessary to obtain knowledge about the used topology type, if there is a change of topology, if a new topology has been registered etc. This has to be established in the management system for each request, which is very disadvantageous in that it is time consuming, laborious and requires a lot of management traffic.
Another disadvantage of existing solutions is that there will always be a delay in the switching arrangement when a MAC address has to be looked up and until for example an SNMP agent in the host CPU (Central Processing Unit) is updated (which is common for all switches).
Still another disadvantage is that some switches start switching traffic before the SNMP agent is started and updated. Then it will not be possible to immediately trace the origin of for example a DHCP (Dynamic Host Configuration Protocol) message and therefore it might not even be possible to detect the topology.
It is clear that such solutions are, if not entirely inapplicable, at least very disadvantageous, slow and prone to errors when new access technologies are introduced (e.g. requiring sites to be close to the end users) and when it is desired to be able to mix different access technologies and line board types.